Mcnamaralundgren5340

The practical applicability of the sensor was successfully evaluated in real vegetable sample and achieved satisfactory recoveries with good precision and accuracy. We developed a paper-based analytical device based on the electropolymerization of poly (3,4-ethylenedioxythipohene) (PEDOT) and graphene oxide (GO) composites on the ITO substrate for the detection of uric acid (UA) in authentic human saliva. Scanning electron microscopy, UV-vis spectrum and X-ray diffraction confirmed the formation of porous PEDOT combined with GO film during the electropolymerization process. The nanocomposite based sensor showed an enhanced electrocatalytic activity toward UA with high sensitivity and stability. We demonstrate that UA can be directly detected in undiluted saliva using the paper-based electroanalytical device with no interference from ascorbic acid and dopamine that are normally present in biological fluids. The results indicated that the developed device is promising for non-invasive monitoring of salivary UA in human body. Two novel electrochemiluminescence (ECL) deoxyribosensors are designed for assay of early lung cancer biomarker (NAP2) using the DNA three-way junction (DNA-TWJ) inserted NAP2 binding aptamer between two double-helical stems and labeled with ruthenium (II) complex (Ru) (NBAT-Ru) taken as molecular recognition element. The signal-off ECL deoxyribosensor was fabricated by covalently coupling the 5'-NH2-(CH2)6-NBAT-Ru to glassy carbon electrode surface modified with 4-aminobenzoic acid (4-ABA). After combining NAP2 and NBAT-Ru, the changed conformation of NBAT-Ru altered the distance between Ru complex and electrode, resulting in a low ECL signal. The signal-on deoxyribosensor was fabricated by self-assembling the 5'-SH-(CH2)6-NBAT-Ru onto the Au electrode. The introduction of NAP2 triggered the conformational change in the aptamer domain, which induces the interhelical stacking of the two double-helical stems of NBAT-Ru. This stacking constitutes "electrical contact," which promotes transmission of electron-holes through the stems of NBAT-Ru, and produces high ECL intensity. Both deoxyribosensors show high sensitivity and selectivity. The biosensors have been successfully applied to clinical plasma detection. The approaches we describe represent unique principles based on DNA-TWJ inserted target special binding domain as molecular recognition element and different immobilization types for the fabrication of biosensors, which are greatly promising for the detection of protein, metal ions, bacteria, and cells. Cadmium (Cd) and lead (Pb) pollution is a significant environmental and human health concern, and methods to detect Cd and Pb on site are valuable. Stencil-printed carbon electrodes (SPCEs) are an attractive electrode material for point-of-care (POC) applications due to their low cost, ease of fabrication, disposability and portability. At present, SPCEs are exclusively formulated from graphitic carbon powder and conductive carbon ink. However, graphitic carbon SPCEs are not ideal for heavy metal sensing due to the heterogeneity of graphitic SPCE surfaces. Moreover, SPCEs typically require extensive modification to provide desirable detection limits and sensitivity at the POC, significantly increasing cost and complexity of analysis. While there are many examples of chemically modified SPCEs, the bulk SPCE composition has not been studied for heavy metal detection. Here, a glassy carbon microparticle stencil printed electrode (GC-SPE) was developed. The GC-SPEs were first characterized with SEM and cyclic voltammetry and then optimized for Cd and Pb detection with an in situ Bi-film plated. The GC-SPEs require no chemical modification or pretreatment significantly decreasing the cost and complexity of fabrication. The detection limits for Cd and Pb were estimated to be 0.46 μg L-1 and 0.55 μg L-1, respectively, which are below EPA limits for drinking water (5 μg L-1 Cd and 10 μg L-1 Pb) [1]. The reported GC-SPEs are advantageous with their low cost, ease of fabrication and use, and attractive performance. The GC-SPEs can be used for low-level metal detection at the POC as shown in the report herein. Spectra matching is widely used in various applications including the search for a spectrum of an unknown compound in an existing spectral database and quality control by means of comparing the spectra of products with standards. In this article, we present a new approach for calculating the similarities of Fourier-transform infrared (FTIR) spectra of organic compounds. Our method, named normalized local change (NLC) approach, incrementally calculates the spectral similarity based on the local spectral shapes. This allows for reducing the bias on the uneven weighing of large and/or broader peaks. In addition, the NLC approach is tolerant to the common issues in spectra matching including baseline offset, baseline sloping, and deviations in wavenumber axis alignment, suggesting its robustness and practical applicability. Performance evaluation confirmed that our NLC approach outperforms commonly used approaches for identifying FTIR spectra of an identical compound in a given dataset. In recent years, layered double hydroxides (LDHs) have garnered a lot of attention in analytical chemistry, due to their advantages such as relatively simple synthesis, low cost, possession of large specific surface area and high catalytic activity, and biocompatibility. The most common applications of LDH in analytical chemistry such as sorbents in sample extraction, electrode materials in electrochemical sensing and color indicators in colorimetric detection have been well reported. Generally, the LDHs are prepared as composites with nanomaterials, or constructed with specific three-dimensional structures, befitting the applications desired for them. However, the applications of LDHs (as extraction sorbents, color indicators and in electrochemical sensing) are usually limited in these scenarios. To help address these challenges, future trends and developmental prospects of LDHs materials in analytical chemistry are discussed in this article. Besides, the strategies associated with the design of LDHs, including the structural aspects, for potential analytical applications are presented and reviewed. The expression level of miRNA-21 is closely related to the occurrence and development of cancer, especially in gastrointestinal cancer. Monitoring miRNA-21 has clinical application in the diagnosis and evaluation of gastrointestinal cancer. A turn-on ratiometric fluorescence bioassay based on the T7 exonuclease-mediated cyclic enzymatic amplification method was developed for miRNA-21 determination by using carbon dots (CDs) and FAM-labeled ssDNA as the signal source. CDs demonstrated the triple functions of built-in internal fluorescence, probe carrier, and quencher in this strategy. In the absence of miRNA-21, FAM-labeled ssDNA would be adsorbed and quenched by CDs. The addition of miRNA-21 induced cycle hydrolysis from the 5' end by the T7 exonuclease and then released the short-cleaved FAM-labeled oligonucleotides. Then, the increased FAM signal (FFAM) and the stable CD signal (FCDs) would be tested through a ratiometric routine for the quantification of miRNA-21. The FFAM/FCDs value showed a good linear relationship with the concentration of miRNA-21 in the range of 0.05-10 nM, and the detection limit for miRNA-21 was 1 pM with excellent selectivity and reproducibility. Furthermore, this sensor successfully evaluated the expression level of miRNA-21 in clinical blood samples from healthy individuals and gastrointestinal cancer patients, and the results were highly consistent with those of qRT-PCR, suggesting the great clinical application value in the diagnosis of cancer associated with miRNA-21 expression levels. Development of a mitochondria-targeting fluorescent probe with large Stokes shift and long-wavelength emission was benefit for accurate detection of hypoxic status, which was known as a major factor of the tumor physiology and influence important pathological processes. However, an efficient optical approach for simultaneously achieving such merits was still lacking. In this work, a turn-on fluorescence probe (HBT-NP) was designed to assess the hypoxic condition of tumor cells by detecting nitroreductase (NTR). Probe HBT-NP was constructed by conjugating 4-nitrobenzyl moiety as reaction site for NTR to 2-(benzo[d]thiazol-2-yl)-4-methylphenol derived fluorescent dye HBT-Py which demonstrated large Stokes shift (Δλ = 243 nm) and long wavelength emission (λem = 640 nm) due to intrinsic mechanism of ESIPT together with ICT process. Upon incubated with NTR, HBT-NP could successively undergo nitro reduction reaction and then release HBT-Py. The reaction mechanism was further confirmed by mass spectra and HPLC analysis, and the docking calculation also indicated that the binding mode and docking affinity of probe HBT-NP with NTR play an important role in catalytic reduction reaction process. As a result, HBT-NP displayed a wide linear range (0.1-1.5 μg/mL) and low detection limit (2.8 ng/mL) response to NTR, and could be used to evaluate hypoxic condition of cancer cells with precise mitochondria-targeting. A new-fangled C3-symmetric triaminoguanidine-pyrrole conjugate has been constructed and utilized for sensing applications. The probe selectively detects zinc ions (Zn2+) by colorimetric as well as turn-on fluorescent manner. Further, the in-situ formed zinc ensemble displays turn-off fluorescence response towards the pyrophosphate anion (PPi) via displacement approach. Emissive off-on-off sensing characteristics of the probe has been successfully exploited to construct the INHIBIT logic gate, coding/decoding of messages and in vivo imaging of Zn2+/PPi in zebrafish larvae. click here Further, PPi detection characteristics of zinc ensembles were established for the sensing of PPi discharged from DNA synthesis and other biological reactions. Possibilities of room temperature spectrometry based on Mn-doped ZnS quantum dots coated with a molecularly imprinted polymer based nanosensor have been explored for the sensitive and selective determination of aflatoxins. Synthesized polymeric nanoparticles exhibit intense room temperature phosphorescence (total decay time of 0.004 s) and aflatoxins quench the room temperature phosphorescence when interact with the recognition cavities of the molecularly imprinted polymer attached to the phosphorescent quantum dots. Room temperature phosphorescence was recorded by scanning from 520 nm to 720 nm (maximum peak intensity at 594 nm) after excitation at 290 nm. The prepared imprinted material was found to have higher adsorption capacity than those based non-imprinted quantum dots, demonstrating high adsorption uptake for aflatoxins. In addition, selectivity studies have demonstrated that the material offers a specific recognition for aflatoxins. Room temperature phosphorescence quenching by aflatoxins was found to be linear within the 2-20 μg L-1 range, and a limit of detection of 3.56 μg kg-1 was obtained. This value was lower than the maximum acceptable/residual level (aflatoxins in feeds) published by the European Commission. The results indicate a simple room temperature phosphorescence nanosensor for aflatoxins detection in fish feed as a versatile tool having excellent sensitivity and selectivity.